This invention relates to a rifle, especially rifles used for hunting and sport purposes, of the type provided with a cylinder lock comprising a receiver and therein a rectilinearly movable and retractable breech bolt having a firing member actuated by a firing spring and a trigger mechanism embodying a trigger and a spring actuated sear having a shoulder which in the cocked position of the sear engages a withdrawable cocking shoulder arranged on the trigger, and a locking lug arranged in the receiver thereby keeping the firing member in a cocked position, said sear being depressed when the rifle is discharged by said firing member under its spring loading into an inoperative position against the action of a spring acting on said sear, the sear shoulder being arranged at the forward end of the sear, and the locking lug passing through an opening in an upwardly open rear portion of the receiver to cooperate with said firing member, and said sear being pivoted at its rear, as well as the rest of the trigger mechanism, in a separate assembly yoke positioned below the receiver, which is generally cylindrical in shape.